12-button, embossed key, membrane switch with integrated window, designed and manufactured for Baxter Healthcare

Switches are used in most electrical devices. Consisting of a conductive path, they are designed to control a circuit. You can press or otherwise engage a switch to open or close the circuit. The electrical device will then respond with the appropriate action.

There are many different types of switches, however. Some of them use a silver printed circuit, whereas others a printed circuit board (PCB). Of those two types, PCB membrane switches have become increasingly popular. To learn more about PCB membrane switches and how they work, keep reading.

An Introduction to PCB Membrane Switches

A PCB membrane switch is a type of switch that’s made of copper-clad laminate or a resin-infused fiber material. Like other switches, it’s designed to control a circuit. PCB membrane switches feature conductive paths. When you press a key or button, the underlying circuit will open or close.

PCB membrane switches are distinguished from other types of switches by their use of a printed circuit board. They contain a circuit board that’s etched with conductive paths. Etching creates one or more conductive paths on a printed circuit, allowing it to function as a switch when combined with the right overlay layer.

The Mechanics of a PCB Membrane Switch

All PCB membrane switches are made of an elastic webbing material that’s able to deform under pressure. After all, that’s why they are known as a “membrane” switch. Membrane switches consist of several layers that are separated by air. These layers are connected by webbing, with membrane switches using an elastic material for the webbing.

As previously mentioned, PCB membrane switches feature conductive paths that are etched into them. These conductive paths serve as the foundation for their circuits. When you engage a PCB membrane switch, the conductive path will be complete.

Advantages of PCB Membrane Switches

When compared to silver printed circuits, PCB membrane switches offer several advantages. For starters, they are better protected against moisture and other environmental contaminants.

PCB membrane switches also support multiple backlighting solutions. Light-emitting diode (LED) is the most common type of backlighting used in PCB membrane switches. It’s energy efficient, long-lasting and provides ample illumination. LEDs, however, can be used in conjunction with light guides to evenly distribute the light across the membrane switch’s overlay layer.

Alternatively, electroluminescent (EL) backlighting can be used in membrane switches. EL backlighting offers many of the same benefits as LED backlighting, making it a viable choice for PCB membrane switches.